Insulated discharge tube terminal



Nov., 22, 1932. F. HOTCHNER 1,888,67l

INSULATED DISCHARGE TUBE TERMINAL Filed March 2l, 1951 l n f l l l n l l 5 /N VEN TOR Patented Nov. 22, 1932 UNITED STATES PATENT OFFICE FRED HOTCHNEB, OF I-.IS ANGEHQIES, CALIFORN'IA INSULATED DISCHARGE TUBE TERMINAL Application led March 21, 1931. Serial No. 524,270.

10 discharge tube signs at the present time is breakdown at the terminals. External insulating devices have proven inadequate, even when made quite bulky, to meet the entire range of conditions common in practice.v The present invention overcomes the various objections to external insulators, reduces the size of holes necessary in the body o' the sign pass the tubes, eliminates any protruding terminai element other than the tube itseian rovide eifective insniation under all weather conditions.

in a previousiy tiled application l Ser' No. 95,6% dated November le, i980, disoiosed T insuiator which anexceet -el thin of gas a acent the wait o e tube to se; as insuiator, toe 'tayer gas being oontaot vv' conductor. ave found there is a resti: 'tive effect tnat may be utiw iized in a thin ver of gas bounded by a dieieetric. object the invention9 ther fore, is provide an .insuiated termina?.

c te restrictiveegeot of an exceed n ingle?` oi gas is utilized to resist brews-down.

other obgeot of the inven 'vioe insuiating body instea o a eonducL ing body as tbe main eiement he assemb ect is to provide insulta may be 'abricated require unusuai care terminal and does with commecialiy A il ing of disch aise serves to oosition the eiement the tube.

. further: obj-eet of one oi the forms the invention is to increase to a very great extent the length of a possible ash-thru discharge by making the passage thru the layer of gas take the form of a helix on considerable length.

Other objects of the invention wili be apparent from the accompanying drawing and the foliowing specification, in which two embodiments of the invention are set forth. it

is to be understood that the invention is not 6@ limited to the particular embodiments shown but may be variously appied in the construisv tion of discharge tube devices and is to limited only by the prior art the einem w Ki J positioned. the snot;i piaoed pac material indicated by 9 'and 10. A suitable material for this packin'g is glass wool, but various other materials may be used. In some cases a metallic packing serves because of the great resistance offered to a discharge by small bodies of gas. This packing also serves as a mechanical support for the bushing and compensates for irregularities in the fabrication of the device as well as' serving.

as a cushion for the bushing. Thefdiameter of the bushing is slightly less than the inside diameter of the section of the tubing in which it is positioned, there being a ver thin layer of gas indicated by 1-1, thru Whic a discharge can not pass under normal conditions, remaining between the bushing and the tube. If this layer of gas is sufficiently thin the resistance is very great and in conjunction with the bushing 8 forms an eii'ective insulator.

While there is a generally accepted theory of the reason for the high resistance of a thin layer of. gas in contact with a conducting body the exact condition 'of a thin la-yer of gas bounded by dielectric material is a matter of speculation. The invention is not to be limited by any theory, the opinion here given being in the way of assisting one practicing the invention in comprehending the device and selecting appropriate materialsfor the same. y

It is known that when conditions exist in a body of gas such that an electron collides with few or .no atoms that conduction can not take place. Given a thin layer of gas and a conducting body in contact with an appreciable boundary of the gas body, once we know the' electrical condition of the conducting body we can judge the probability of electron movement and predict the behavior of thedevice. Given a` thin body of gas bounded by dielectric material we are confronted with the problem of charges on the surface of the dielectric material and the rate ofchange of the charges, an altogether battling subject and one which is still in the state of the art shrouded with much obscurity. It is my belie` that the reason for the operation of the device is that material ionization does not occur in the gas layer by diffusion from the ionized column in the main chamber of the tube because of the very few atoms being exchanged between the two chambers, particularly in the form of the invention in which i a packing. ring of discharge stopping material intervenes. The device is thus not burdened with dissipating charges due to the action in the tube and we have to consider the result of charges set up by the electrostatic stress between the activated column-and the outside conducting body, or which is nearly the same thing, -on outside body capable of. holding a-rnaterial charge. lhe action then is the same problem'we have to deal with in a condenser plate, which is that of a displacement of electrons and positive particles along the lines of stress. The length of any such movement being here reduced to such a degree that ionization 1by collision is veryimprobable, we thus realize in the direction of the lines of stress much the same insulating effect that we experience in a. device such as set forth in my aforesaid copcnding application. A break down lengthwise thru the gas isresisted by thel restrictive effect of a thin body and the packing.

In the form of the invention shown in Figure 3, I provide means to cut up the thin layer of gas intov a helix so as to greatly lengthen the break down path through the gas from the main body of the gas in the tube to the plane of the supporting body. The packing in this case also serves as a mechanical support and cushion for the bushing.

In the device shown in Figures 1 and 2 I provide protuberances on vthe bushing indicated by 12, 12, etc. to position it accurately within the tube. In the latter form these protuberances are eliminated andthe packing itself being wound around the bushing serves to locate it accurately in the center of the tube, thus compensating for slight irregularities in commercial glass tube.

In Figure 3 the tube proper is indicated by numeral 20, the electrode end by 21, the electrode proper by 22, the lead in conductor by 23, and the supporting body by 25. A portion of the tube, indicated by 24, is of enlarged diameter and encloses the insulating bushing 26 which is located between the shoulders 27 and 28 of the section 24. The bushing has a helical groove, 31, in which a cord packing of discharge stopping material such as glass, Wool is placed. This packing should be suiiciently compressible to compensate for the variation in diameter in commercial glass tube.

Having thus described my invention, what I claim is:

1. In a discharge tube, an internal insulator for preventing break down from the inside of said tube to an external body consisting of a dielectric body Within said tube in the path of a possible break down discharge, the main portion of said dielectric body being out of contact with the portions of the Wall4 of said tube immediately adjacent thereto leaving a very small space therebetween in which the probability'of ionization occurring upon the application of electric stress is s-o reduced that the said space serves as additional insulation, the length of a possible break down passage from the main chamber in said tube to any possible break down point on the wall of saidtube near said dielectric body being of such length that theprobability of such break down is reduced to a. verylow value.

. 2. In a. discharge tube, an internal insulator tor'prcventing break down from the inside oi s aicl tube to an external body consisting of a dietectric body Within said tube in the path of a possible break down discharge,

the main portion of said dielectric body being out of Contact with the portions of the wall of said tube immediately adjacent thereto leaving a very small space therebetween in which the probability offionzation occurring upon the applcation of electric stress is so reduced that the said space serves as additional insulation, and means to prevent a break down discharge from the main chamber in said tube thru saidspace to a possible break down point on the wall of said tube near said dielectric body.

3. In a discharge tube, an internal insulator for preventing break down from the inside of said tube to an external body consisting of a dielectric body within said tube in the path of a possible break down discharge, the main portion of said dielectric body being out of contact with the portions of the wall of said tube immediately adjacent thereto leaving a very small space therebetween in which the probability of ionization occurring upon the application of electric stress is so reduced that said space serves as additional insulation, and discharge stopping means between said space and the main chamber ot said discharge tube.

"4. In a discharge tube, an internal insulator for preventing break down from the inside of said tube to an external body consisting of a dielectric body within said tube in the path of a possible break down discharge, the main portion of said dielectric body being out of contact with the portions of the wall of said tube immediately adjacent theretoY leaving a very small space therebetween in which the probability of ionization occurring upon the application of electric stress is so reduced that said space serves as additional insulation, and-a packing body of discharge stopping material interposed between said space and the main chamber of said tube.

5. In a discharge tube, an internal insulator for preventing break down from the inside of said tube to an external body consisting of a dielectric body within said tube in the path of a possible break down discharge, the main portion of said dielectric body being out of contact with the portions of the wall of said tube immediately adiacent thereto leaving a very small space therebetween in which the probability of ioniza-,

tion occurring upon the application of electric stress is so reduced that said space serves as additional insulation, and a packing of discharge stopping material between said dielectric body and the adjacent Wall of said tube in the path of a possible break down discharge between said body and saidiwall 'thru said spacer ti. In a discharge tube, an internal insulator for preventing break down from the inupon the application of electric stress is so Y reduced that said space serves as additional insulation, and a helical packing of discharge stopping material between said body and the adjacent Wall of said tube disposed to cut said space into a helix whereby to greatly in` crease the length of a possible discharge thru saidspace from the main `chamber in said tube by causing the same'to take a helical v course.

7. In a discharge tube, an internal insulator for preventing, break ldown from' the inside of said tube to an external body consisting of a dielectric bushing positioned within said tube in the path of a possible break down discharge having an outside diameterislightly less than the inside diameter of the surrounding tube wall, a helical groove in said bushing and a helical packing of discharge stopping material in said groove bearinfr against said wall and locating said bushing within the said tube.

. 8. In a gaseous conduction tube mounting wherein the tube is mounted upon a support and extends thru a conductive portion thereof, means'for preventing break down disL charge from the interior of the tube to said portion consisting of a dielectric 'bushing within said tube, and extending on opposite sides of said portion.

9. In a gaseous conduction tube mounting wherein the tube is mounted upon a support and extends thru a conductive portion thereof, means for preventing break down discharge :trom the interior of the tube to said portion consisting of a dielectric bushing within said tube the main portion of which is out of Contact with the Wall of said tube immediately adjacent thereto leaving a very small space therebetween.

10. In a gaseous conduction tube mounting wherein the tube is mountedupon a support and extends thru a conductive portion thereof, means for preventing break down discharge from the interior of the 'tube to portion consisting of a dielectric bushing within said tube extending1 substantial distance along the wall of the tube on both sides of said portion, the main ortion of said bushing being out of `contact with the adjacent wall of the tube leaving a very small space therebetween in wl' "ch the probability or ionization occurring` upon the application of electric stress is so reduced that`A said space serves as additional insulation.

11. a gaseous conduction tube mounting wherein the tube is mounted upon a supaes` port and extends thru a conductive portion to prevent break down'discharge thru said' space from the main chamber of said tube.

y12.v In a gaseous conduction tube mounting wherein the tube is mounted upona support and extends thru a conductive portion thereof, means for preventing break down discharge from the interior ofthe tube to said portion consisting of a dielectric bushing within said tube extending a substantial distance along the wall of the tube on both sides of said portion, the main portion of said bushing being out of contact with the adjacent; wall ofthe -tube leaving avery small space therebetween in which the probability of ionilzation occurring upon th'e application of elecspacetherebetween in which the probability of ionization occurring upon the application of electric stress is so reduced that said rspace serves as additional insulation, and a plurality of annular barriers of discharge stopping material in the path of any possible break downv discharge from the main chamber of said tube thru said space.

Signed at Chicago, Illinois, this 19th day of March, 1931.

FRED HorcHNEn.

tric stress is so reduced that said space servesv as additional insulation, and packing means yof discharge Stopping material separating said space from the main chamber of .said tube.

13. In a gaseous conduction tube mounting wherein the tube is mounted-upon a support and extends thru a conductive portion there'- of, means for preventing break down 4discharge from the interior of the tube to said portion consisting of a dielectric bushing within said tube extending a substantial distance along the wall of the tube on both sides of said portion, the main portion of said bushing being out'of Contact withv the adjacent wall of the tube leaving a very small space therebetween in which the probability of ioni-4 zation occurring upon the application of elec-v tric stress is so reduced that said space serves as additional insulation, and a helical packing of discharge stopping material between said bushing and the adjacent wall of said tube cutting said space into a helix to increase to a considerable extent the length of a possible break down discharge from the main chamber of said tube thru sai-d space.

'14. In a gaseous conduction tube mounting wherein the tube is mounted upon a support and extends thru a conductive portion thereof, means for preventing break down discharge from the interior of thc tube to said portion consisting of a dielectric bushing within said tube extending a substantial distance along the wall of the tube on both sides of said portion, the main portion of said bushing being out of contact with the adjacent Wall of said tube leaving a very small 

